A method for manufacturing a semiconductor device using a salicide process, which includes forming a gate dielectric layer over a silicon substrate including a PMOS region and an NMOS region; forming a first silicon pattern in the NMOS region and a second silicon pattern in the PMOS region; forming a first metal layer that is in contact with the first silicon pattern and the exposed first portion of the silicon substrate; and forming a first gate, a first junction, a second gate, and a second junction by performing a heat treatment to silicify the respective first and second silicon patterns and the silicon substrate.